California State Route 1 in western San Mateo County traverses the Montara Mountain spur of the Santa Cruz Mountains. In modern times California State Route 1 passes through Montara Mountain via the Tom Lantos Tunnels and the highway is traditionally associated with Devils Slide. Although Devils Slide carries an infamous legacy due it being prone landslides it pales in comparison to the alignment California State Route 1 carried prior to November 1937 over Old Pedro Mountain Road.
Old Pedro Mountain Road opened to traffic in 1915 and is considered one of the first major asphalted highways in California. Old Pedro Mountain Road clambers over a grade from Montara towards Pacifica via the 922 foot high Saddle Pass. Pictured above an overlook of Old Pedro Mountain Road facing southward towards Montara as it appears today. Pictured below it the same view during June 1937 when it was part of the original alignment of California State Route 1. Today Old Pedro Mountain sits abandoned and eroding away as part of a trail within Montara State Beach.
Part 1; the history of Old Pedro Mountain Road
Prior to Old Pedro Mountain Road travel over Montara Mountain (sometimes referred to as San Pedro Mountain) was difficult. Prior to the arrival of Europeans a well established Native American overland trail existed over Montara Mountain. This trail was replaced in 1879 when San Mateo County completed the Half Moon Bay-Colma Road as a stage route. The Half Moon Bay-Colma Road was built largely west of Old San Pedro Mountain Road above the modern Tom Lantos Tunnels. The general path of the Half Moon Bay-Colma Road can be seen traversing Montara Mountain on the 1882 Bancroft's Map of California and Nevada.
During the early 20th Century the Half Moon Bay-Colma Road reportedly was incredibly difficult for early automobiles to traverse as it was extremely narrow and featured grades as high as 25%. The Half Moon Bay-Colma Road can be seen in greater detail between Montara north towards Rockaway Beach (now in Pacifica) on the 1914 C. F. Weber & Company Map of San Mateo County.
CA 1/LRN 56 can be seen traversing Old Pedro Mountain Road on the 1935 Division of Highways Map of San Mateo County. CA 1/LRN 56 can be seen approaching Old Pedro Mountain Road through Farallone City and Montara via; Farallone Boulevard, 4th Street, Audubon Avenue, George Street and Elm Street. CA 1/LRN 56 can be seen entering Rockaway Beach on what is now Higgins Way.
The final climb to Saddle Pass winds through the overgrown on Old Pedro Mountain Road to a trail marker with directions to Montara and Pacifica.